Final answer:
Diarrhea would not require a CPT code as it is a condition, not a procedure like Mastectomy, Otoplasty, and Hysterectomy which do require CPT codes.
Step-by-step explanation:
The Current Procedural Terminology (CPT) code system is used to describe medical, surgical, and diagnostic services and procedures performed by healthcare professionals. In the options provided, Diarrhea would not require a CPT code, because it is a symptom or medical condition rather than a procedure.
On the other hand, a Mastectomy, Otoplasty, and Hysterectomy are all surgical procedures, which do require CPT codes to be assigned for billing and documentation purposes.